Althougn we have made a few experiments with mag- 

 netic fields, we have not yet come to any conclusions as to 

 whether or no there are y pairs which have become loosened 

 in the attachment of positive to negative, forming a softer and 

 more ionizing radiation. Their existence might be suspected 

 since there is an analogous effect in the case of X-rays ; and 

 probably they would be found more at the back of the pene- 

 trated plate than in front of it. 



A few further experimental illustrations are shown dia- 

 grammatically in Figs. 5-7, with the explanations attached. 





40-3 



2^c 



Fiff. 5. 



The upper figure shows the general arrangement. The lower 

 figures are diagrammatic, and show the currents tor different ar- 

 rangements of the Pb and Al at the bottom of the chamber, and 

 at the top, with the exception of the plate through which the 

 7 rays enter. Inverting the top plates makes little difference 

 where the upper of the two plates at the bottom is Al, but an 

 appreciable difference Avhen it is Pb, because in the latter case 

 a good deal of secondary radiation is thrown upwards by the 

 Pb, and there is a tertiary from the top plate. 



The same, when the conical opening is completely filled by 

 a Pb stopper : — 



12-6 12-6 17-7 18-3 



The differences show the effects of those rays only which do 

 not pass through the Pb stopper: — 



27-7 28-7 39-9 44-7 



Fig. 6. 



These show the effect of 

 inverting that portion 

 only of the top plate 

 where the 7 rays enter. 

 Three Pb plates = -oo cm., 

 Al plate = -16 cm. 



